Is there any secret other finding a perfectly level spot to keep the pad/bag from sliding "downhill" (in a Lunar Duo)? I'm a side sleeper which takes his bag with him so straps wouldn't work for that part though the bigger issue seems to be keeping the pad from moving on the floor so my son doesn't end up on top of me by morning if he's uphill. We now swapped spots since I wake up more often and will scoot myself and pad back to my side of the tent. Some silicone sealer on the floor only works marginally until there's enough grime to wear off the "stick". I'd imagine the same if applied to the pad. Just one of those things to deal with?

Maybe try getting a gossamer gear thinlight pad 1/8 inch thick and sticking a small section of it under your pad. A thinlight only weighs 2 oz for a 60 inch long piece... and I imagine you could get away with using only a small section of that, less than an ounce. The thinlight can do double duty as something to sit on.

It's not so much sticky on any side, rather the closed cell foam is "tacky". It'll keep itself in place under pressure against silnylon. I find my montbell pillow also stays right under my head when laid against the thinlight.